From field to health: a simple way to increase the nutraceutical content of grape as shown by NO-dependent vascular relaxation

Influence of Benzothiadiazole on the Accumulation and Metabolism of C6 Compounds in Cabernet Gernischt Grapes (Vitis vinifera L.)

Pre-harvest application of elicitors improves grape quality, specifically the phenolic compounds and color characteristics. Limited research has been conducted on the impact of elicitors on the C6 compounds found in grapes. This is due to lack of comprehensive studies examining the combined effects of bound aroma compounds, enzyme activity, and substrate availability. This study aimed to assess the impact of benzothiadiazole (BTH) on the physicochemical properties and C6 compounds of Cabernet Gernischt grapes during ripening. Compared with the control group (CK), BTH treatment significantly increased the 100-berry weight, skin/berry ratio, pH, total phenolic content, and total flavonoid content in ripe grapes. Additionally, BTH treatment led to significant reductions in reducing sugar, total soluble solids, titratable acidity, linoleic acid, linolenic acid, and free C6 aldehydes. Furthermore, BTH treatment significantly decreased the contents of free C6 alcohols and increased the levels of free and bound C6 esters. BTH treatment also increased the activities of lipoxygenase, alcohol dehydrogenase, and alcohol acetyltransferase enzymes, while it decreased the activity of hydroperoxide lyase enzyme. The application of BTH resulted in changes to the physicochemical properties and levels of C6 compounds in Cabernet Gernischt grapes by up-regulating enzyme activity and down-regulating precursors.

Vasorelaxant Effects Induced by Red Wine and Pomace Extracts of Magliocco Dolce cv

Several epidemiological studies demonstrate that moderate (red) wine consumption may afford protection against cardiovascular diseases. Protection is ascribed to the biological activity of wine components, many of which, however, are discarded during winemaking. In vitro rat thoracic aorta rings contracted with phenylephrine or KCl were used to assess the vasorelaxant activity of extracts from wine pomaces (seeds and skins) of the Calabrian autochthonous grape variety Magliocco dolce (Arvino). NMR spectroscopy was used to ascertain their chemical composition. Data demonstrate that seed and skin, but not must, extracts are capable of relaxing vascular preparations in an endothelium-dependent manner, similarly to the red wine extract, due to the presence of comparable amounts of bioactive constituents. In rings pre-contracted with 20–30 mM KCl, only seed extracts showed a moderate relaxation. The most efficacious vasodilating extract (wine) showed a good antioxidant profile in both [(2,2-diphenyl-1-picrylhydrazyl)acid] radical (DPPH) and [2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)] radical (ABTS) assays. In conclusion, winemaking from Magliocco dolce grape can provide potentially health-promoting by-products useful in cardiovascular disease management.

Sustainable Crop Protection, Global Climate Change, Food Security and Safety-Plant Immunity at the Crossroads

The development of novel strategies of plant disease management is crucial in view of the growing demand of sustainability in agri-food chains. The use of agrochemicals is not without risk for the consumer and environment in terms of their residues in food, feed, water bodies and harmful effects on nontarget organisms. However, because of the high global annual yield losses attributable to plant diseases and also due to global climate changes that have exacerbated some phytosanitary emergences, chemical input in agriculture is mandatory. In this complex scenario, the use of agrochemicals that boost the plant immune system represents a relatively novel approach in crop protection. These plant protection products are not antimicrobial or fungicidal agents, but include both natural and synthetic elicitors and plant activators that only target the host immune system, with no biocide mechanism of action. In general, these products present a number of strengths: they leave no residue and should not select resistant pathogen strains, they can be used to control virus diseases, and can increase the levels of bioactive phytochemicals in plant foods.

Proteomic and metabolic traits of grape exocarp to explain different anthocyanin concentrations of the cultivars

The role of grape berry skin as a protective barrier against damage by physical injuries and pathogen attacks requires a metabolism able to sustain biosynthetic activities such as those relating to secondary compounds (i.e., flavonoids). In order to draw the attention on these biochemical processes, a proteomic and metabolomic comparative analysis was performed among Riesling Italico, Pinot Gris, Pinot Noir, and Croatina cultivars, which are known to accumulate anthocyanins to a different extent. The application of multivariate statistics on the dataset pointed out that the cultivars were distinguishable from each other and the order in which they were grouped mainly reflected their relative anthocyanin contents. Sorting the spots according to their significance 100 proteins were characterized by LC-ESI-MS/MS. Through GC-MS, performed in Selected Ion Monitoring (SIM) mode, 57 primary metabolites were analyzed and the differences in abundance of 16 of them resulted statistically significant to ANOVA test. Considering the functional distribution, the identified proteins were involved in many physiological processes such as stress, defense, carbon metabolism, energy conversion and secondary metabolism. The trends of some metabolites were related to those of the protein data. Taken together, the results permitted to highlight the relationships between the secondary compound pathways and the main metabolism (e.g., glycolysis and TCA cycle). Moreover, the trend of accumulation of many proteins involved in stress responses, reinforced the idea that they could play a role in the cultivar specific developmental plan.

Increasing the phenolic compound content of grapes by preharvest application of abcisic acid and a combination of methyl jasmonate and benzothiadiazole

Benzothiadiazole (BTH) and methyl jasmonate (MeJ) have been described as exogenous elicitors of some plant defense compounds, polyphenols among them. Given that they activate different arrays of biochemical reactions to induce resistance, the objective of this study was to determine whether the joint application of BTH and MeJ to grape clusters affects the level of the main flavonoid compounds in grapes and in the resulting wines. The results are compared with those obtained when abscisic acid (ABA), a plant growth regulator involved in several physiological processes, was sprayed in the same vineyard. The results obtained indicated that, although the application of ABA increased the content of skin anthocyanins and tannins, these positive effects were not reflected in the wines made from these grapes. BTH+MeJ-treated grapes also presented higher anthocyanin and flavonol contents, and in this case, their wines presented better chromatic characteristics that the wine made from control grapes.

Improving grape phenolic content and wine chromatic characteristics through the use of two different elicitors: methyl jasmonate versus benzothiadiazole

Benzothiadiazole (BTH) and methyl jasmonate (MeJ) have been described as exogenous elicitors of some plant defense compounds, polyphenols among them. The objective of this study was to determine whether the application of BTH or MeJ to grape clusters at the beginning of the ripening process had any effect on the accumulation of the main flavonoid compounds in grapes (anthocyanins, flavonols, and flavanols) and the technological significance of these treatments in the resulting wines. The results obtained after a 2 year experiment indicated that both treatments increased the anthocyanin, flavonol, and proanthocyanidin content of grapes. The wines obtained from the treated grapes showed higher color intensity and total phenolic content than the wines made from control grapes. The exogenous application of these elicitors, as a complement to fungicide treatments, could be an interesting strategy for vine protection, increasing, at the same time, the phenolic content of the grapes and the resulting wines.

From vineyard to glass: agrochemicals enhance the melatonin and total polyphenol contents and antiradical activity of red wines

Resistance inducers are a class of agrochemicals, including benzothiadiazole and chitosan, which activate the plant own defence mechanisms. In this work, open-field treatments with plant activators were performed on two red grape (Vitis vinifera L.) varieties cultivated in different localities, Groppello (Brescia, Lombardia, Italy) and Merlot (Treviso, Veneto, Italy). Treatments were carried out every 10 days until the véraison and, after harvesting, experimental wines (microvinificates) were prepared. In general, both melatonin and total polyphenol content, determined by mass spectrometry and Folin-Ciocalteu assay, respectively, were higher in wines produced from grapes treated with resistance inducers than in those obtained from untreated control and conventional fungicide-treated grapes. Accordingly, antiradical power of wines derived from plant activator-treated grapes, measured by both DPPH (2,2-diphenyl-1-picrylhydrazyl) and the ABTS [(2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical-scavenging assay, was higher than in their counterparts. To the best of our knowledge, this is the first report on the effects of agrochemicals on the melatonin content of red wine.

Managing phenol contents in crop plants by phytochemical farming and breeding-visions and constraints

Two main fields of interest form the background of actual demand for optimized levels of phenolic compounds in crop plants. These are human health and plant resistance to pathogens and to biotic and abiotic stress factors. A survey of agricultural technologies influencing the biosynthesis and accumulation of phenolic compounds in crop plants is presented, including observations on the effects of light, temperature, mineral nutrition, water management, grafting, elevated atmospheric CO(2), growth and differentiation of the plant and application of elicitors, stimulating agents and plant activators. The underlying mechanisms are discussed with respect to carbohydrate availability, trade-offs to competing demands as well as to regulatory elements. Outlines are given for genetic engineering and plant breeding. Constraints and possible physiological feedbacks are considered for successful and sustainable application of agricultural techniques with respect to management of plant phenol profiles and concentrations.

Bioactivity of Grape Chemicals for Human Health

Grapevine ( Vitis vinifera) products, grape and grape juice, represent a valuable source of bioactive phytochemicals, synthesized by three secondary metabolic pathways (phenylpropanoid, isoprenoid and alkaloid biosynthetic routes) and stored in different plant tissues. In the last decades, compelling evidence suggested that regular consumption of these products may contribute to reducing the incidence of chronic illnesses, such as cancer, cardiovascular diseases, ischemic stroke, neurodegenerative disorders and aging, in a context of the Mediterranean dietary tradition. The health benefits arising from grape product intake can be ascribed to the potpourri of biologically active chemicals occurring in grapes. Among them, the recently discovered presence of melatonin adds a new element to the already complex grape chemistry. Melatonin, and its possible synergistic action with the great variety of polyphenols, contributes to further explaining the observed health benefits associated with regular grape product consumption.

Regulation of the phenolic profile of berries can increase their antioxidant activity

The changes of the antioxidant activities (AOA), antiradical activities (ARA), low-density lipoprotein (LDL) oxidation, and total contents of phenolics, anthocyanins, flavonols, hydroxybenzoic acids, and hydroxycinnamic acids in black currant and black chokeberry, after treatment with ornithine decarboxylase inhibitor, a polyamine inhibitor (O-phosphoethanolamine, KF), and a phenol biosynthesis stimulator (carboxymethyl chitin glucan, CCHG), were analyzed spectrophotometrically. Gallic acid, hydroxycinnamic acids, and selected flavonol contents was analyzed by RP-HPLC. Both regulators increased the AOA measured as inhibition of peroxidation (IP) in black chokeberry, 1.71-fold after treatment with KF(1) and 1.74-fold after treatment with CCHG. In black currant IP was elevated after CCHG application only in lower dose (CCHG(1) 63.36% vs control 53.23%). In black chokeberry the total phenolics content was elevated 1.49-fold after KF(1) application and 1.31-fold after CCHG(2) application. The regulators had the lower effect on the phenolic accumulation in black currant. There was a strong relationship between the total phenolics in the both crops and anthocyanins, hydroxybenzoic acids, and hydroxycinnamic acids contents, respectively. Both regulators significantly changed the ratio of conjugated (rutin) to free (quercetin) flavonol mainly in black chokeberry. The antioxidant activities compared using LDL in vitro oxidation assay were increased more expressively after treatment with KF(2) in both crops.

Grapes and human health: a perspective

Grapes are a valuable source of numerous phytonutrients, including the intensively studied constituent, resveratrol. A question worth addressing is the potential of dietary grape consumption to positively modulate human health. Many studies have suggested cardiovascular benefits, and some work has indicated cancer chemopreventive activity. Data are particularly compelling in the area of skin cancer prevention. With financial support provided by the California Table Grape Commission, novel and exciting preliminary data are emerging from independent research suggesting beneficial activity against other less prevalent but devastating illnesses, such as Alzheimer's disease and urinary bladder dysfunction. It is further suggested that some of the copious amounts of data obtained with resveratrol may be relevant to grape consumption, especially responses that can be mediated by low concentrations of the substance. Whether future specific health claims will be sought from or allowed by regulatory authorities is not known, but based on existing data, it is clear that grapes should be considered an integral component of fruit and vegetable enriched diets that are recommended by health authorities and widely accepted as beneficial for human health and disease prevention.

Proteome changes in the skin of the grape cultivar Barbera among different stages of ripening

Background

Grape ripening represents the third phase of the double sigmoidal curve of berry development and is characterized by deep changes in the organoleptic characteristics. In this process, the skin plays a central role in the synthesis of many compounds of interest (e.g. anthocyanins and aroma volatiles) and represents a fundamental protective barrier against damage by physical injuries and pathogen attacks. In order to improve the knowledge on the role of this tissue during ripening, changes in the protein expression in the skin of the red cultivar Barbera at five different stages from véraison to full maturation were studied by performing a comparative 2-DE analysis.

Results

The proteomic analysis revealed that 80 spots were differentially expressed throughout berry ripening. Applying a two-way hierarchical clustering analysis to these variations, a clear difference between the first two samplings (up to 14 days after véraison) and the following three (from 28 to 49 days after véraison) emerged, thus suggesting that the most relevant changes in protein expression occurred in the first weeks of ripening. By means of LC-ESI-MS/MS analysis, 69 proteins were characterized. Many of these variations were related to proteins involved in responses to stress (38%), glycolysis and gluconeogenesis (13%), C-compounds and carbohydrate metabolism (13%) and amino acid metabolism (10%).

Conclusion

These results give new insights to the skin proteome evolution during ripening, thus underlining some interesting traits of this tissue. In this view, we observed the ripening-related induction of many enzymes involved in primary metabolism, including those of the last five steps of the glycolytic pathway, which had been described as down-regulated in previous studies performed on whole fruit. Moreover, these data emphasize the relevance of this tissue as a physical barrier exerting an important part in berry protection. In fact, the level of many proteins involved in (a)biotic stress responses remarkably changed through the five stages taken into consideration, thus suggesting that their expression may be developmentally regulated.

LDL isolated from plasma-loaded red wine procyanidins resist lipid oxidation and tocopherol depletion

Dietary phenolic compounds may act as antioxidants in vitro, but because of structural modifications during absorption, its role based on concentrations high enough to afford an antioxidant protection needs to be re-evaluated. We have explored the hypothesis that red wine procyanidins interact with low density lipoproteins (LDL) and that, at this location, the phenolic compounds efficiently protect LDL from oxidation and maintain LDL alpha-tocopherol at a high steady state concentration by recycling it back from the alpha-tocopheroxyl radical. To this end, human plasma was supplemented with wine procyanidins and isolated LDL were challenged with a constant flux of peroxyl radicals. As compared with LDL from plasma-free procyanidins, those LDL better resisted lipid oxidation and exhibited longer lag-phases of alpha-tocopherol consumption. The procyanidins, depending on their structure, were able to reduce the UV-induced alpha-tocopherol radical in a micellar system, as evidenced by electron paramagnetic ressonance. Mechanistically, the protection of LDL was interpreted in terms of quenching of peroxyl radicals and the recycling of alpha-tocopherol by the procyanidins bound to the lipoproteins. These results support the notion that, in human plasma, the procyanidins, via binding to LDL, may act as efficient local antioxidants.

Processing blackcurrants dramatically reduces the content and does not enhance the urinary yield of anthocyanins in human subjects

Blackcurrant (BC) fruits are a rich source of biologically active anthocyanins but little is known of the anthocyanin content of commonly consumed BC products or how processing affects the absorption. We report that whereas fresh and frozen whole BC were a rich source of anthocyanins, containing 897 and 642mg (100gFW)(-1) of total anthocyanins the levels in all other products were substantially lower (0.05-10.3% of the levels in fresh fruit). Further, when the absorption and excretion of BC was assessed in volunteers consuming a portion (100g) of frozen whole BC (642mg total anthocyanins) and, 300g of a BC drink made by diluting concentrated syrup (33.6mg total anthocyanins), only small quantities of BC anthocyanins were excreted in urine (fruit, 0.053±0.022%; drink, 0.036±0.043%; mean percent urinary yield±SD) and they were not detected in plasma. These data indicate that fresh and frozen BC, but not processed products, are rich sources of anthocyanins but, regardless of the food source, these anthocyanins are poorly bioavailable.

A standard addition method to assay the concentration of biologically interesting polyphenols in grape berries by reversed-phase HPLC

A reversed-phase HPLC method which allows the simultaneous assay of (+)- catechin, (-)-epicatechin, trans-resveratrol, quercetin and quercetin glycosides in grape berries is described. Kromasil 100 served as stationary phase and a gradient of acetic acid, water and methanol was used. The analytical run requires 42 min for complete sample elution. Satisfactory peak resolution was achieved following a novel extraction process and direct injection of a 20 microL sample. The method was used for the analyses of eighteen samples. Linearities were in the range of 0.98 to 0.999 regression coefficient, for all phenolics, while detection limits ranged from 30 microg mL(-1) for trans-resveratrol to 1.5 mg mL(-1) for (+)-catechin. Recoveries ranged from 95.1 to 98.7% while the method provided good precision, with standard deviations between 3.5 and 6.1%, n=5.

Benzothiadiazole induces the accumulation of phenolics and improves resistance to powdery mildew in strawberries

Benzothiadiazole (BTH) enhanced the accumulation of soluble and cell-wall-bound phenolics in strawberry leaves and also improved the resistance to powdery mildew infection under greenhouse conditions. The most pronounced change was seen in the levels of ellagitannins, which increased up to 2- to 6-fold 4 days after the BTH application, but persisted only in the inoculated plants. The induction of phenolic metabolism by BTH was also reflected in the fruits, several compounds being increased in inoculated, BTH-treated plants. Basal salicylic acid (SA) content was high in strawberry leaves, but increased in a similar fashion to other phenolics after the treatments. Several phenolic compounds were identified in strawberries for the first time. For example, ellagic acid deoxyhexose, three agrimoniin-like ellagitannins, sanguiin H-10- and lambertianin C-like ellagitannins in the leaves, ellagic acid, p-coumaric acid, gallic acid, and kaempferol hexose in the cell-wall-bound fraction of the leaves, and kaempferol malonylglucoside in the fruits. The findings show that BTH can enhance the accumulation of phenolics in strawberry plants which may then be involved in the BTH-induced resistance to powdery mildew.